Full bore set down tool assembly for gravel packing a well

ABSTRACT

A full bore set down tool assembly provides a housing attached to a packer in a wellbore and aligned with the production zone. A service tool of the tool assembly is attached to a tubing string extending to the surface and is adapted for selective, removable attachment to and positioning within the housing. The tool assembly defines a downstream flow path and a return flow path when the service tool is attached to the housing. A ball valve that is selectively shiftable from the surface opens and closes the return flow path to define a circulate position and a squeeze position. The housing, service tool, and ball valve also define a reverse position. The tool assembly facilitates gravel packing of the annulus between the wellbore casing and the service string including the tool assembly.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] The present invention relates to the field of well tools. Morespecifically, the invention relates to a device and method for gravelpacking a well that also allows for perforating or fracturing a well ina single trip and that allows full bore access through the device andwith weight set down on the device.

[0003] 2. Related Art

[0004] Techniques are well known in the oil and gas industry forcontrolling sand migration into wells penetrating unconsolidatedformations by gravel packing the wells. Sand migration and collapse ofunconsolidated formations can result in decreased flow and production,increased erosion of well components, and production of well sand whichis a hazardous waste requiring specialized handling and disposal. Suchgravel packing typically consists of depositing a quantity, or “pack,”of gravel around the exterior of a perforated liner and screen, with thepack preferably extending into the perforations in the unconsolidatedformation. The gravel pack then presents a barrier to the migration ofthe sand while still allowing fluid to flow from the formation. Inplacing the gravel pack, the gravel is carried into the well and intothe formation in the form of a slurry, with much of the carrier fluid orworkover fluid being returned to the surface, leaving the gravel in thedesired location.

[0005] Attempts have been made in the past to minimize the number oftrips of the tool string into the well. Each trip of the tool stringinto a well takes an appreciable amount of time, and therefore incurssignificant costs in terms of rig and crew time. As will be readilyapparent, these costs are dramatically increased if the tool string istripped to a great depth in a well. Further, previous devices allow forthe use of perforating guns attached to the bottom of the gravel packtool assembly so that the perforating and gravel pack may be completedin a single trip. The same is true for fracturing equipment which may beattached to prior tool assembles to facilitate fracturing and gravelpacking in a single trip.

[0006] One problem associated with prior designs relates to control andpositioning of the tool assembles. As fluid from the surface is pumpedthrough the tubing and into the well to complete the gravel pack, thetubing tends to shrink due to the temperature differential between thesurface and the bottom of the wellbore where the gravel pack isperformed. Additionally, other factors may contribute to or cause tubingshrinkage. The tubing shrinkage may create uncertainty as to thepositioning of the tool assembly in relation to the packer, sand screen,and other gravel pack components. Some tool assemblies rely on theposition of the tool assembly in relation to the fixed downholecomponents required for the gravel pack to determine the function of andflow paths through the tool assembly. Thus, uncertainty in thepositioning of the tool assembly may cause the tool assembly toinadvertently shift from one operation to another. For example, thedistance between a circulate position and a squeeze position in oneprior tool is only about 18 inches. Shrinkage may move the tool fromsqueeze to circulate changing the flow paths and operation of the tool.Similarly, in operations performed from a floating platform, the deckheave can change the position of the tool assembly causing uncertaintyin the tool assembly positioning. Accordingly, there is a need for agravel pack tool assembly that eliminates the uncertainty associatedwith the positioning of the tool assembly and the operating position ofthe tool assembly.

[0007] Another problem associated with prior tool assembles is that theyblock or restrict the size of the bore through the tool assembly. Therestriction limits the ability to perform operations below the toolassembly. For example, in a tool assembly that includes the perforatingequipment attached to the bottom of the tool, the manner of actuatingthe perforating guns is limited. One preferred manner of actuating theperforating guns is to drop a detonation bar through the tubing intoengagement with the perforating guns to fire the guns. Typical toolassembles that restrict or block the tubing do not allow a detonationbar to pass therethrough. Thus, the use of a detonation bar in such anoperation is not possible. Consequently, despite the use of the priorart features, there remains a need for a tool assembly that provides forfull bore diameter through the tool assembly to allow for operations tobe performed through the tool assembly, such as logging operations,and/or to allow the passage of well tools, such as wireline andslickline tools, logging tools, chemical cutters, drop balls,detonation/drop bars, and the like, through the tool assembly.

SUMMARY

[0008] To achieve such improvements, the present invention provides afull bore, set down tool assembly that provides a full bore diameterthrough the tool, in one preferred embodiment, and that is set in apacker in the wellbore in constant compression when in at least thecirculate and squeeze positions to ensure the proper positioning andoperation of the tool assembly. In general, the tool assemblyincorporates a shiftable ball valve to alternate between a circulate andsqueeze positions. When in the open position, the ball valve providesfor full bore access through the tool assembly and in the closedposition substantially prevents flow through the return path of the toolassembly to allow for a squeeze or reverse operation.

[0009] One aspect of the present invention provides a tool assembly foruse in a tool string for gravel packing an annular area of a wellboresurrounding at least a portion of the tool string in the wellbore. Thetool assembly includes a packer and a housing attached to the packer.The housing defines a bore therethrough and at least one orificeprovides communication between an exterior of the housing and the bore.A service tool of the tool assembly is selectively attachable to atubing string and is adapted for selective positioning within thehousing. A selectively shiftable ball valve mounted within the servicetool is selectively and remotely shiftable between an open position anda closed position. The service tool defines at least two alternate flowpaths and the ball valve is adapted and positioned to selectively openand close at least one of the alternate flow paths.

[0010] The tool assembly also includes a downstream flow path of thealternate flow paths and a return path of the alternate flow paths withthe ball valve positioned in the return flow path. The housing, theservice tool, and the ball valve define and are shiftable between atleast a squeeze position, a circulating position, and a reverseposition.

[0011] One aspect of the present invention includes an attachment memberadapted for selective releasable attachment of the service tool to thehousing. The attachment member includes a collar attached to the housingand a collet attached to the service tool with the collar and the colletadapted for cooperative, releasable mating attachment. The housing, theservice tool, and the ball valve define and are shiftable between atleast a squeeze position and a circulating position and the attachmentmember is adapted to attach the service tool to the housing when thehousing, the service tool, and the ball valve are in the squeezeposition and the circulating position.

[0012] In one preferred embodiment, the ball valve defines a valvepassageway therethrough when the ball valve is in the open position. Theservice tool defines a service tool bore therethrough that comprises atleast a portion of one of the at least two alternate flow paths. Thediameter of the valve passageway is substantially equal to the diameterof the service tool bore. Further, the service tool bore and the valvepassageway are sized and adapted to permit passage of a well tooltherethrough.

[0013] Another aspect of the present invention provides a tool assemblyfor use in a tool string for gravel packing an annular area of awellbore surrounding at least a portion of the tool string in thewellbore. The tool assembly includes a housing assembly that defines afirst flow path and a second flow path. A ball valve of the housingassembly is adapted to selectively open and close one of the first andsecond flow paths and the first and second flow paths are adapted toprovide fluid communication of a gravel pack material and a returnfluid. The ball valve defines a valve passageway therethrough when theball valve is in an open position. Preferably, the diameter of the valvepassageway is about equal to the diameter of the associated one of thefirst and second flow paths within which the ball valve is positioned.

[0014] Yet another aspect of the present invention provides a gravelpack assembly for use in a tool string for gravel packing an annulararea of a wellbore surrounding at least a portion of the tool string inthe wellbore. The gravel pack assembly includes a packer and a housinghaving a first end and a second end. The housing defines a boretherethrough and at least one orifice that provides fluid communicationbetween an exterior of the housing and the bore. The housing is attachedto the packer proximal the first end of the housing. Typically, a sandscreen is attached to the housing proximal the second end of thehousing. The screen is adapted to allow the flow of fluids therethrough.A service tool is selectively attachable to and positionable within thehousing and defines a downstream flow path and a return flow path. Thedownstream flow path communicates with the bore of the housing when theservice tool is positioned therein. The return path communicates withthe sand screen. The service tool has a valve in the return flow paththat is adapted to selectively open and close the return flow path tocontrol the flow of fluid therethrough. The diameter of the openingthrough the valve when the valve is open is substantially equal to thediameter of the bore so that the valve is adapted to provide accesstherethrough without substantially reducing the cross sectional area anddiameter of the bore. Further, the service tool, the housing, and theball valve define at least a squeeze position and a circulating positionwhen the service tool is attached to the housing. The service tool andthe housing are adapted to support compressive loading when attached.When the service tool is detached from the housing, the service tool,the housing, and the ball valve define at least a reverse position.

[0015] Still yet another aspect of the present invention provides a toolassembly for performing a gravel pack. The tool assembly includes aservice tool adapted for selective attachment to a service string. Theservice tool defines a downstream flow path and a return paththerethrough. Also included is a valve within the return pathselectively moveable between an open position and a closed position andadapted to control the flow through the return path. The valve isadapted to provide a full bore opening therethrough when in the openposition.

[0016] Another selected embodiment comprises a housing attached to thepacker that defines a bore therethrough. A service tool is adapted forselective, removable mating with the housing. An attachment member isadapted for selective, releasable attachment of the service tool and thehousing. The service tool is selectively shiftable between at least acirculating position and a squeeze position; and the attachment memberis engaged to attach the service tool to the housing when the servicetool is in the circulating position and the squeeze position.

[0017] Another aspect of the present invention provides a method ofgravel packing a well using a tool assembly that defines at least adownstream flow path and a return flow path and has a ball valve in thereturn path. The method includes positioning the tool assembly in thewell and selectively shifting the tool assembly between at least acirculate position and a squeeze position to perform the gravel pack andactuating the ball valve to a open position in the circulating positionand a closed position in the squeeze position.

[0018] Yet another aspect of the present invention provides a toolassembly for performing a gravel pack that includes a tool assembly bodywith means for directing fluid through the tool assembly body to performthe gravel pack; means for selectively blocking a return flow throughthe body to define at least a squeeze position and a circulatingposition; and means for supporting a load on the tool assembly body whenthe tool assembly body is in at least the squeeze position and thecirculating position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The manner in which these objectives and other desirablecharacteristics can be obtained is explained in the followingdescription and attached drawings in which:

[0020]FIG. 1 is schematic view of a service string including the presentinvention positioned in a well.

[0021] FIGS. 2A-D are a partial cross sectional, side elevational of thepresent invention in the squeeze position.

[0022]FIG. 3 is a top view of the ball valve.

[0023]FIG. 4 is a schematic view of the j-slots in the squeeze position.

[0024] FIGS. 5A-D are a partial cross sectional, side elevational of analternative embodiment of the present invention in the squeeze position.

[0025]FIG. 6 is a schematic view of the j-slots in the squeeze position.

[0026] FIGS. 7A-D are a partial cross sectional, side elevational of thepresent invention in the circulate position.

[0027]FIG. 8 is a schematic view of the j-slots in the circulateposition.

[0028] FIGS. 9A-E are a partial cross sectional, side elevational of thepresent invention in the return position.

[0029]FIG. 10 is a schematic view of the j-slots in the return position.

[0030] It is to be noted, however, that the appended drawings illustrateonly typical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention generally provides a full bore, set downtool assembly that provides a full bore diameter through the tool, inone preferred embodiment, and that is set in a packer in the wellbore inconstant compression when in at least the circulate and squeezepositions to ensure the proper positioning and operation of the toolassembly. In general, the tool assembly incorporates a shiftable ballvalve to alternate between a circulate and squeeze positions. When inthe open position, the ball valve provides for full bore access throughthe tool assembly and in the closed position substantially prevents flowthrough the return path of the tool assembly to allow for a squeeze orreverse operation.

[0032]FIG. 1 is a schematic view of a wellbore 1 having a service string3 therein. The service string 3 includes a perforating gun aligned withthe zone to be produced, a bottom packer 5, a sand screen 6, a gravelpack tool assembly 10, and a tool assembly packer 7. The service string3 is supported by a tubing string 8 extending to the surface. In thisembodiment, the perforating guns fire perforating the production zone.Then, the service string 3 is lowered to align the packers above andbelow the perforations and the packers are set isolating the productionzone and defining an annulus area between the service string 3 and thecasing 2. The gravel pack is then performed and the zone produced. Thepresent invention is useful in such an operation as well as otheroperations requiring a gravel pack, and is useful in operations otherthan those requiring perforation and gravel packing in a single trip.

[0033] A typical gravel pack operation includes three operations (amongothers) referred to as the squeeze operation, the circulating operation,and the reverse operation. In the squeeze operation, the gravel slurryis forced out into the formation 4 by pumping the slurry into theproduction zone while blocking the return flow path 46. The absence of areturn flow path 46 causes the pressure to build and force the slurryinto the formation 4. When the void spaces within the formation 4 are“filled,” the pressure will rise quickly, referred to as “tip screenout.” Upon tip screen out, the next typical step is to perform acirculating operation in which the gravel slurry is pumped into theannular area 9 between the sand screen 6 and the casing 2. In thecirculating position, the return flow path 46 is open and the returnfluid is allowed to flow back to the surface. The sand screen 6 holdsthe gravel material of the gravel slurry in the annular area 9 butallows fluids to pass therethrough. Thus, circulating the gravel slurryto the sand screen 6 deposits the gravel material in the annular area 9.However, during the circulating operation, when the deposited gravelmaterial reaches the top of the sand screen 6, the pressure will riserapidly indicating screen out and a full annulus. Note that analternative manner of operating the tool is to perform the squeezeoperation with the tool assembly 10 in the circulate position and with asurface valve (not shown) closed to prevent return flow. Using thismethod, the shift from the squeeze operation to the circulate operationmay be made by simply opening the surface valve and without the need toshift the tool.

[0034] When the annulus is packed, the string may be pulled from thewellbore 1. However, to prevent dropping of any gravel materialremaining in the service string 3 and the tubing 8 into the well whenpulling the string from the well, the gravel in the tubing 8 and servicestring 3 is reverse circulated to the surface before the string isremoved. This procedure of reverse circulating the remaining gravel fromthe well is referred to as the reverse operation. In general, the flowof fluid is reverse circulated through the tubing 8 to pump the gravelremaining in the tubing string 8 and service string 3 to the surface.

[0035] Generally, because bridging may occur when depositing the gravelin the well creating gaps in the gravel pack, the squeeze and/orcirculating operations may be performed more than once for each gravelpack operation. This is referred to as “restressing the pack.” Thereverse operation may be performed before restressing the packing orbetween the squeeze and circulate operations as desired.

[0036] A tool assembly 10 facilitates the gravel pack operation. As usedherein, the terms squeeze position, circulating position, and reverseposition shall refer to a position of the tool assembly corresponding tothe squeeze operation, the circulating operation, and the reverseoperation respectively.

[0037] Also, for the purposes of this discussion, the terms “upper” and“lower,” “up hole” and “downhole,” “up,” “down,” and “upwardly” and“downwardly” are relative terms to indicate position and direction ofmovement in easily recognized terms. Usually, these terms are relativeto a line drawn from an upmost position at the surface to a point at thecenter of the earth, and would be appropriate for use in relativelystraight, vertical wellbores. However, when the wellbore 1 is highlydeviated, such as from about 60 degrees from vertical, or horizontal,these terms do not make sense and therefore should not be taken aslimitations. These terms are only used for ease of understanding as anindication of what the position or movement would be if taken within avertical wellbore 1.

[0038] FIGS. 2A-D are a cross sectional elevational view of onepreferred embodiment of the tool assembly 10 (also referred to as thegravel pack assembly). The tool assembly 10 generally comprises ahousing 12 attached to a packer 7 and a service tool 14 adapted forremovable attachment to the housing 12. By shifting the service tool 14and controlling the relative positioning of the service tool 14 to thehousing 12, the tool assembly 10 is shiftable between the squeeze,circulating, and reverse positions. When viewed in combination, thehousing 12 and service tool 14 are also referred to herein as thehousing assembly 16.

[0039] The housing 12 has an elongated tubular body defining a bore 20therethrough. At least one orifice defined by the housing 12 extendsthrough a side wall 24 of the housing 12 to provide fluid communicationbetween the bore 20 and an exterior 26 of the housing 12. A first end 28of the housing 12, typically, the upper end, is attached to, or proximalto, a packer 7. When set, the packer 7 maintains the position of thepacker 7 and the housing 12 relative to the production zone and preventstheir movement within the wellbore 1. Note that the packer 7 may definea portion of the housing 12. Attached to a second, or bottom, end 30 ofthe housing 12 is the sand screen 6.

[0040] The service tool 14 has a generally cylindrical body sized andadapted to fit within and mate with the bore 20 of the housing 12. Theservice tool 14 is adapted for selective, releasable attachment to andpositioning of at least a portion thereof within the housing 12. Afirst, or upper, end 34 of the service tool 14 is adapted for attachmentto the tubing string 8 such as by threaded connection, with the servicetool bore 60 in fluid communication with the tubing string 8. Tofacilitate the gravel pack operation, the service tool 14 defines atleast two alternate flow paths 38, comprising at least first and secondflow paths, 40 and 42 respectively. In general, one flow path, thedownstream flow path 40, delivers the gravel pack material in thecirculating and squeeze operations; and the other, second flow pathprovides the return path 42.

[0041] The alternate flow paths 38 are adapted to provide a live annuluswherein the well annulus above the service tool packer 7 communicateswith the formation while the service tool 14 is in use. Thus, if pumpingis halted, the operator can still monitor the pressure below the packer7. Prior systems do not provide a live annulus.

[0042] The service tool 14 is releasably attachable to the housing 12 byan attachment member 48. In general, the attachment member 48 is adaptedto temporarily attach the service tool 14 to the housing 12 and tosupport a load necessary to keep a compressive load on the service tool14. In the preferred embodiment shown in FIG. 1, the service tool 14 isattached to the housing 12 with the attachment member 48 engaged duringthe circulate and squeeze operations. The service tool 14 is detachedand the attachment member 48 disengaged during the reverse operation.Attaching the service tool 14 to the housing 12 during the squeeze andcirculate operations ensures that the tool assembly 10 is in the properposition during the relevant operations and provides added reliability.The relatively high load capacity of the attachment member 48 allows thetool assembly 10 to operate with weight set down on the tool assembly10, further adding to the reliability of the tool.

[0043] In one embodiment, the attachment member 48 comprises a collar 50attached to the housing 12 defining a profile 52 therein. A collet 54attached to the second, bottom end 36 of the service tool 14 is adaptedfor releasable, cooperative mating with the profile 52 of the collar 50.The spring force, or snap force, of the collet 54 provides a resistanceto upward movement and detachment of the collet 54 from the collar 50offering a resistance to detachment and providing the operator withassurance of proper relative positioning of the service tool 14 and thehousing 12. During shifting of the service tool 14, the collet 54 ispulled from the collar 50 and then, typically, forced back into thecollar 50. The resistance offered by the snap force of the collet 54provides a positive indication at the surface to the operator that thetool 14 has shifted. Other similar attachments of the service tool 14 tothe housing 12 are readily apparent to those skilled in the art and are,therefore, considered a part of the scope of the present invention.Further, the attachment member 48, in one alternative embodiment (notshown), is replaced with a shoulder adapted to support the loadrequirements. In this alternative embodiment, the service tool 14 is not“attached” to the housing 12, but is maintained in the housing 12 bysubstantially maintaining a downward force on the service tool 14.

[0044] The service tool 14 defines a service tool bore 60 extendinglongitudinally therethrough. Service tool orifices 62 (at least one)extend through the wall of the service tool 14 and provide fluidcommunication between the service tool bore 60 and an exterior 64 of theservice tool 14. The service tool orifices 62 are positioned in theservice tool 14 such that, when the service tool 14 is positioned in andattached to the housing 12, so that the tool assembly 10 is in thecirculating or squeeze position, the service tool orifice 62communicates with an housing assembly annulus 66 formed between theservice tool 14 and the housing 12. The housing orifices 22 are alsopositioned to communicate with the housing assembly annulus 66. Seals 68mounted above and below the service tool orifice 62 and the housingorifices 22 seal the top and bottom of the housing assembly annulus 66between the service tool 14 and the housing 12. Accordingly, the servicetool orifices 62, the housing assembly annulus 66, and the housingorifices 22 provide a fluid communication passageway from the servicetool bore 60 to the annular area 9 between the tool assembly 10 and thecasing 2 of the wellbore 1 when the tool assembly 10 is in thecirculating or squeeze positions. Thus, the service tool bore 60 and theservice tool orifice 62 define a downstream flow path 40 through theservice tool 14; the service tool bore 60, the service tool orifice 62,the housing assembly annulus 66 and the housing orifice 22 define adownstream flow path 40 through the housing assembly 16 that providescommunication between the tubing string 8 and the annulus formed betweenthe service string 3 and the wellbore 1 when the tool assembly 10 is inthe circulating or squeeze positions.

[0045] A plug 70 in the service tool 14 positioned below the servicetool orifices 62 prevents flow through the service tool bore 60 beyondthe plug 70. In alternative embodiments, the plug 70 is either fixed andintegral with the body of the service tool 14 or is a removable plug 70(FIGS. 5A-D) that is adapted for selective insertion and placementwithin the service tool bore 60. For example, in those embodiments thatrequire a full open bore through the tool assembly 10 to provide apassageway for a well tool, such as a detonation/drop bar, a ball, alogging tool, a wireline or slickline tool, a chemical cutter, and thelike, through the tool assembly 10, the insertable type plug 70 isrequired. Using the insertable type plug 70, the well tool is passedthrough the tool assembly 10 prior to inserting the plug 70. The toolassembly 10 is then operated with the plug 70 in place.

[0046] The service tool 14 further defines at least one, but preferablya plurality of, return passageways 74 extending longitudinally throughthe wall of the service tool 14. The inlets 76 to the return passageways74 are positioned on a side of the plug 70 opposite to the position ofthe service tool orifices 62 so that the plug 70 prevents fluidcommunication between the service tool orifices 62 and the returnpassageway 74 inlets 76 via the service tool bore 60. Further, thereturn passageways 74 are offset from the service tool orifices 62 inthe wall of the service tool 14 to prevent communication therebetween.The outlets of the return passageways 74 are positioned proximal thefirst, upper end of the service tool 14 and communicate with an exterior64 of the service tool 14. Therefore, the return passageways 74 providefluid communication between the service tool bore 60 below the plug 70to the exterior 64 of the service tool 14 at a position proximal thefirst, upper end of the service tool 14. The outlets 78 of the returnpassageways 74 are positioned in the service tool 14 such that when thetool assembly 10 is in the circulating or squeeze position the outlets78 are above the packer 7 providing communication between the annulusformed between the tubing string 8 and the casing 2 and the service toolbore 60 below the plug 70. The service tool bore 60 below the plug 70and the return passageways 74 are collectively referred to herein as thereturn path 42.

[0047] A ball valve 80 (FIG. 3 is a top view of the ball valve 80) ofthe service tool 14 is provided in the return path 42, specifically inthe service tool bore 60 below the plug 70 in one preferred embodiment.The ball valve 80 is adapted to move between an opened position and aclosed position. In the closed position, the ball valve 80 substantiallyseals the service tool bore 60 preventing flow through the return path42. In the open position, the ball valve 80 permits fluid flowtherethrough and through the return path 42. Further, in the preferredembodiment, the ball valve 80 defines a valve passageway 82, when in theopen position, that has a diameter that is substantially about equal tothe diameter of the service tool bore 60 to provide full bore accessthrough the service tool 14. Thus, the service tool bore 60 and thevalve passageway 82 are sized and adapted to permit a well tool to passtherethrough providing a full bore passageway through the tool assembly10. The ball valve 80, in one preferred embodiment, includes anenergized seal 84 (a spring loaded seal) to ensure sealing between theball and the service tool bore 60.

[0048] Note that, although the preferred embodiment is described as aball valve 80, the present invention may incorporate any type of valve80 that is capable of providing a valve passageway 82 capable ofproviding a full open bore therethrough that does not substantiallyreduce the cross sectional area of the bore through the service tool 14to allow passage of well tools through the tool assembly 10.

[0049] A shifting mechanism 90 of the service tool 14 actuates the ballvalve 80 between the open and closed positions. An upper portion 92 ofthe service tool 14 is free to move axially relative to a lower portion94 of the service tool 14 within a predefined limited range. Therelative axial movement is achieved when the lower portion 94 isattached to the housing 12 by way of the attachment mechanism. The upperportion 92 is then moved axially by an operator controlling the positionof the tubing string 8 from the surface. Thus, the operator moves thetubing string 8 and, thus, the upper portion 92 of the service tool 14providing relative movement between the upper and lower portions, 92 and94, actuating the shifting mechanism 90. Note that the snap force of thecollet 54 provides a positive indication that the tool 14 has shifted.

[0050] The shifting mechanism 90 comprises a mandrel 96 positioned inthe service tool 14 such that it is free to spin relative to theremainder of the service tool 14. The mandrel 96 has a series of j-slots98 (well know in the art) adapted to mate with a pin 100 fixed to lowerportion 94 of the service tool 14. The j-slots 98 and pin 100 cooperateto produce a predetermined rotation (such as 45°) of the mandrel 96 foreach up or down cycle of the upper portion 92 relative to the lowerportion 94. FIGS. 4, 8, and 10 show the j-slots 98 and pin 100positioned for the squeeze, circulate, and reverse positionsrespectively. The shape, positioning, and length of the j-slots 98 incooperation with an interconnected control lug member 102 and matingcontrol lug receiver 104 are adapted to selectively limit the allowableaxial movement of the upper portion 92 relative to the lower portion 94.A yolk 106 attached to the mandrel 96 at one end is attached to the ballvalve 80 at the opposite end and is adapted to move axially within theservice tool 14. The movement of the mandrel 96 and the control lugmember 102 control the position of the yolk 106 to selectively open andclose the ball valve 80 in response to relative movement of the upperportion 92 of the service tool 14 to the lower portion 94. In onepreferred embodiment, the valve 80 is closed upon pickup and open uponevery other set down of the service tool 14.

[0051] In operation, the tool assembly 10 is typically run into thewellbore 1 with the service tool 14 attached to the housing 12 and thedownstream flow path 40 providing a reference pressure with the annulusand the tubing string 8. The tool assembly 10 may be run into thewellbore 1 with the ball valve 80 in either the open or closed position.Once in the proper position, the packers are set and the housing 12position is established.

[0052] As discussed, in general the first operation is the squeezeoperation (FIGS. 2A-D, 4, and 5A-D). In the squeeze operation, theservice tool 14 is attached to the housing 12 and the ball valve 80 isclosed preventing flow through the return path 42. The gravel slurry ispumped down through the tubing string 8 into the service tool bore 60,through the downstream flow path 40, and into the annulus between theservice string 3 and the casing 2. The return path 42 is blocked,therefore, the pressure builds forcing the gravel slurry into theformation 4 until pressure rises rapidly indicating “tip screen out.”

[0053] Once tip screen out occurs, the tool assembly 10 is shifted tothe circulating position (FIGS. 7A-D and 8) by lifting and lowering thetubing to move the upper portion 92 of the service tool 14 the requirednumber of times, as defined by the shifting mechanism 90 (see FIG. 8 forthe j-slot position), to shift the service tool 14 and move the ballvalve 80 to the open position (FIG. 7C). During the shifting of theservice tool 14, collet 54 of the attachment member 48 is pulled fromthe collar 50 providing a surface indication that the tool has shifted.Thus the snap force of the collet 54 is selected to provide the desiredsurface indication. The collet 54 is forced back into the collar 50 tofurther shift the tool assembly 10. This shifting process is repeated asnecessary When in the open position the return path 42 is open. Thegravel slurry is pumped through the tubing string 8 to the service toolbore 60, through the downstream flow path 40, and into the annulusbetween the service string 3 and the wellbore casing 2 below the toolassembly packer 7 where the gravel material is deposited. The returnfluid flows through the sand screen 6, into the service tool bore 60through the second, lower end below the plug 70, through the return path42 of the service tool 14, and into the annulus between the tubingstring 8 and the casing 2 at a point above the packer 7. The returnfluid then flows to the surface. Upon screen out, the circulatingoperation is stopped. The squeeze and circulating operations may berepeated as needed by simply shifting the service tool 14 as describedto selectively open and close the ball valve 80.

[0054] After the circulating and squeeze operations are complete, thereverse operation is typically performed in preparation of pulling theservice string 3 from the wellbore 1. To position the service tool 14 inthe reverse position (FIGS. 9A-E and 10), the tool assembly 10 isshifted by lifting the tubing to move the upper portion 92 of theservice tool 14, as defined by the shifting mechanism 90 (see FIG. 10for the j-slot position), to shift the service tool 14 and move the ballvalve 80 to the closed position (in the preferred embodiment shown, theball is closed upon pick-up of the service tool 14). The attachmentmember 48 is then detached releasing the service tool 14 from thehousing 12 typically by pulling up on the tubing string 8 withsufficient force to release the actuating mechanism. Then, the servicetool 14 is lifted from the housing 12 to a position at which at leastthe service tool orifices 62 are positioned above the packer 7. The wellis reverse circulated pumping “clean” fluid down through the annulus,through the service tool orifices 62 into the service tool bore 60, upthrough the service tool bore 60 into the tubing string 8, and throughthe tubing string 8 to the surface. Any gravel slurry remaining in thetubing string 8 and the service tool bore 60 is forced to the surfacewith the exception possibly of a small amount deposited between theservice tool orifices 62 and the ball valve 80.

[0055] While the foregoing is directed to the preferred embodiment ofthe present invention, other and further embodiments of the inventionmay be devised without departing from the basic scope thereof, and thescope thereof is determined by the claims which follow. It is theexpress intention of the applicant not to invoke 35 U.S.C. § 112,paragraph 6 for any limitations of any of the claims herein, except forthose in which the claim expressly uses the words “means for” together.

I claim:
 1. A tool assembly for use in a tool string for gravel packingan annular area of a wellbore surrounding at least a portion of the toolstring in the wellbore, the tool assembly comprising: a packer; ahousing attached to the packer, the housing defining a bore therethroughand further defining at least one orifice providing communicationbetween an exterior of the housing and the bore; a service toolselectively attachable to a tubing string and adapted for selectivepositioning within the housing; a selectively shiftable ball valvemounted within the service tool, the ball valve selectively, remotelyshiftable between an open position and a closed position; the servicetool defining at least two alternate flow paths; and the ball valveadapted and positioned to selectively open and close at least one of theat least two alternate flow paths.
 2. The tool assembly of claim 1 ,further comprising: a downstream flow path of the at least two alternateflow paths; a return path of the at least two alternate flow paths; andthe ball valve positioned in the return flow path.
 3. The tool assemblyof claim 1 , further comprising: the housing, the service tool, and theball valve defining and shiftable between at least a squeeze positionand a circulating position.
 4. The tool assembly of claim 3 , furthercomprising: the housing, the service tool, and the ball valve alsodefining and shiftable between a reverse position.
 5. The tool assemblyof claim 1 , further comprising: an attachment member adapted forselective releasable attachment of the service tool to the housing. 6.The tool assembly of claim 5 , wherein the attachment member furthercomprises: a collar attached to the housing; a collet attached to theservice tool; the collar and the collet adapted for cooperative,releasable mating attachment.
 7. The tool assembly of claim 5 , furthercomprising: the housing, the service tool, and the ball valve definingand shiftable between at least a squeeze position and a circulatingposition. the attachment member adapted to attach the service tool tothe housing when the housing, the service tool, and the ball valve arein the squeeze position and the circulating position.
 8. The toolassembly of claim 1 , further comprising: the ball valve defining avalve passageway therethrough when the ball valve is in the openposition; the service tool defining a service tool bore therethrough,the service tool bore comprising at least a portion of one of the atleast two alternate flow paths; and the diameter of the valve passagewaysubstantially equal to the diameter of the service tool bore.
 9. Thetool assembly of claim 8 , further comprising: the service tool bore andthe valve passageway sized and adapted to permit passage of a well tooltherethrough.
 10. A tool assembly for use in a tool string for gravelpacking an annular area of a wellbore surrounding at least a portion ofthe tool string in the wellbore, the tool assembly comprising: a housingassembly defining a first flow path and a second flow path; a ball valveof the housing assembly adapted to selectively open and close one of thefirst and second flow paths; and the first and second flow paths adaptedto provide fluid communication of a gravel pack material and a returnfluid.
 11. The tool assembly of claim 10 , further comprising: the ballvalve defining a valve passageway therethrough when the ball valve is inan open position; the diameter of the valve passageway is about equal tothe diameter of the associated one of the first and second flow pathswithin which the ball valve is positioned.
 12. A gravel pack assemblyfor use in a tool string for gravel packing an annular area of awellbore surrounding at least a portion of the tool string in thewellbore, the assembly comprising: a packer; a housing having a firstend and a second end, the housing defining a bore therethrough and atleast one orifice providing fluid communication between an exterior ofthe housing and the bore; the housing attached to the packer proximalthe first end of the housing a sand screen adapted to allow the flow offluids therethrough in fluid communication with the housing, the sandscreen positioned below the second end of the housing; a service toolselectively attachable to and positionable within the housing, theservice tool defining a downstream flow path and a return flow path; thedownstream flow path communicating with the bore of the housing when theservice tool is positioned therein; the return path communicating withthe sand screen; the service tool having a valve in the return flowpath, the valve adapted to selectively open and close the return flowpath to control the flow of fluid therethrough; and the valve adapted tocontrol the flow through the return flow path.
 13. The gravel packassembly of claim 12 , further comprising: the diameter of the openingthrough the valve when the valve is open is substantially equal to thediameter of the bore so that the valve is adapted to provide accesstherethrough without substantially reducing the cross sectional area anddiameter of the bore.
 14. The gravel pack assembly of claim 12 , furthercomprising: the service tool, the housing, and the ball valve definingat least a squeeze position and a circulating position when the servicetool is attached to the housing.
 15. The gravel pack assembly of claim14 , further comprising: the service tool and the housing adapted tosupport compressive loading when attached.
 16. The gravel pack assemblyof claim 12 , further comprising: the service tool, the housing, and theball valve defining at least a reverse position when the service tool isdetached from the housing.
 17. A tool assembly for performing a gravelpack, the tool assembly comprising: a service tool adapted forselective, attachment to a service string; the service tool defining adownstream flow path and a return path therethrough; a valve within thereturn path selectively moveable between an open position and a closedposition and adapted to control the flow through the return path; andthe valve adapted to provide a full bore opening therethrough when inthe open position.
 18. A gravel pack assembly, comprising: a housingattached to the packer, the housing defining a bore therethrough; aservice tool adapted for selective, removable mating with the housing;an attachment member adapted for selective, releasable attachment of theservice tool and the housing; the service tool selectively shiftablebetween at least a circulating position and a squeeze position; theattachment member engaged to attach the service tool to the housing whenthe service tool is in the circulating position and the squeezeposition.
 19. A method of gravel packing a well using a tool assemblydefining at least a downstream flow path and a return flow path andhaving a ball valve in the return path, the method comprising:positioning the tool assembly in the well; and selectively shifting thetool assembly between at least a circulate position and a squeezeposition to perform the gravel pack, and actuating the ball valve to aopen position in the circulating position and a closed position in thesqueeze position.
 20. A tool assembly for performing a gravel pack, thetool assembly comprising: a tool assembly body; means for directingfluid through the tool assembly body to perform the gravel pack; meansfor selectively blocking a return flow through the body to define atleast a squeeze position and a circulating position; means forsupporting a load on the tool assembly body when the tool assembly bodyis in at least the squeeze position and the circulating position.